Heterojunctions from Coulomb-Engineered Transition Metal Dichalcogenides

The band structure and the band gap of semiconducting layered materials are strongly affected by the Coulomb interaction between carriers within the layer. At the same time we can externally modify this interaction by means of dielectric substrates or dielectric coating. This Coulomb-engineering can thus be used to tailor the fundamental electronic properties of layered materials.

Here we use a combination of the GdW [1] and WFCE [2] approaches to systematically study the environmental-screening effects to monolayers of semiconducting transition metal dichalcogenides on a material-realistic level. We compare static and dynamic screening effects of homogeneous substrates and derive an effective modeling scheme for spatially-varying heterogeneous substrates. The latter allows for the external and non-invasive induction of heterojunctions within the otherwise homogeneous mononalyer. Our calculations show that spatial band gap modulations on the length scale of a few lattice constants are possible and are just limited by the heterogeneous substrate.

[1] M. Rohlfing, Phys. Rev. B 82, 205127 (2010)
[2] M. Rösner et al., Phys. Rev. B 92, 085102 (2015)